Machines are already known that permit the corrugation of sheets of flexible material, running in a continuous way, the corrugations being produced substantially perpendicular to the running direction of the sheets.
Hence, FR patent 2 079 499 describes a corrugating machine comprising two parallel shafts, rotatably driven in opposite directions. Carrier arms for corrugating bars are fixed onto these shafts, the bars being parallel to the shafts. In addition two endless belts are fitted to grip between them the sheet of flexible material and bring it to the point of maximum interpenetration of the corrugating bars.
When it is inserted between the corrugating bars of each shaft, the flexible sheet takes a corrugated shape, the depth of the corrugations depending on the spacing of the shafts.
One can also mention another type of corrugating device, in which the corrugating devices are carried by stirrup pieces rigidly fixed to an endless chain. The corrugating bars are thus driven by the endless chain which is, in part, parallel to the plane along which the sheets of flexible material are passing. These sheets are carried by spaced apart dryer bars which ensure that they pass along and which are perpendicular to their running direction.
The endless chain is driven by at least two shafts parallel to the dryer bars.
When a corrugating bar arrives opposite a sheet of flexible material, it is engaged in the empty space provided between two dryer bars. The corrugating bar stays in contact with the flexible sheet as long as it is parallel to the plane of the dryer, then, driven by the endless chain, it disengages itself from the dryer bars. The flexible sheet thus takes on a corrugated shape. The depth of the corrugations depends on the distance between the shafts driving the endless chain and the dryer bars.
Japanese Patent Application JP-60 115 332 is known which describes a machine for forming radiator fins. During the formation of these metal fins, heads carried on an endless belt come into contact with the flat strip of metal to form corrugations in it. During the contact, the heads are driven in a rotation movement with respect to the strip and several corrugations are simultaneously formed.
These corrugating devices have been used for numerous years and they have given satisfaction.
However, the design of known corrugating devices limits the depth of the corrugations. In effect, if the two systems of bars are too close to each other, they cannot penetrate one into the other either on engagement or on disengagement of the corrugating bars. The machine cannot operate.
In addition, experience has shown that with continuous running, the corrugations must be made one after another and not simultaneously, which limits the upper values of radii of curvature for the return parts of the chains.
Indeed, it appears to be necessary to provide profiled materials having corrugations that are relatively deep and close together. The resistance to bowing of such materials is increased compared with traditional profiled materials. This allows an increase in the strength of roofs in which they are used.
Furthermore, the materials with deep corrugations are better suited to laying tiles in certain applications.
A new corrugating machine has therefore been designed in order to provide materials having a profile of the sinusoidal type and, in particular a profile marked with deep corrugations.